Has the HVAC Diagnostic System Check been performed?

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Go to Step 2

Go to Diagnostic System Check Manual System

or Diagnostic System Check Automatic System

1. If the engine is at operating temperature, allow the engine to cool to room temperature.
2. Ensure that the ignition key is in the OFF position.
3. Connect an R-134a manifold gage set to the low side and high side service ports on the vehicle refrigerant system.
4. Check the low and high side pressures.

The low and high side pressure readings should be almost equal to each other once the system has come to rest.

Are both the low and high side pressures above the specified value?

345 kPa (50 psi)

Go to Step 6

Go to Step 3

Are both the low and high side pressures below the specified value?

69 kPa (10 psi)

Go to Step 4

Go to Step 5

1. Add 0.45 Kg (1 lb) of R-134a.
2. Leak test the refrigerant system. Refer to Leak Testing .
3. Repair the refrigerant leak.
4. Recheck the low and high side refrigerant pressures.

Are both the low and high side refrigerant pressures above the specified value?

345 kPa (50 psi)

Go to Step 6

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1. Leak test the refrigerant system. Refer to Leak Testing .
2. Repair the refrigerant leak.
3. Recheck the low and high side refrigerant pressures.

Are both the low and high side refrigerant pressures above the specified value?

345 kPa (50 psi)

Go to Step 6

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1. Start the engine and allow the engine to idle.
2. Depress the mode control button until the UPPER position is displayed (automatic system).
3. Turn the A/C ON by depressing the A/C button on the HVAC control head.

Does the compressor clutch engage?

--

Go to Step 7

Go to HVAC Compressor Clutch Does Not Engage Manual System or HVAC Compressor Clutch Does Not Engage Automatic System

1. Accurately measure and record both the ambient air humidity level and temperature.

(These figures will be used later.)

2. The engine still idling in PARK.
3. Install a precision thermometer into the I/P center air outlet.
4. Set the HVAC control head to the following positions:

•	A/C button to ON

•	Temperature control to full cold

•	Mode control button to UPPER (I/P outlets)

•	Blower switch to the maximum high speed.

5. Elevate and maintain the engine speed at 1000 RPM.
6. Allow the low and high side pressure readings to stabilize, if necessary.

(Stabilization usually requires 2-3 minutes.)

7. Record the low and high side pressure readings.
8. Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart.

Refer to

A/C System Pressure Zone Classification



.

Do both the low and high side pressures fall within Zone A on the classification chart?

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Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone A

Go to Step 8

Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart. Refer to

A/C System Pressure Zone Classification

Do both the low and high side pressures fall within Zone B on the classification chart?

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Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone B

Go to Step 9

Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart. Refer to

A/C System Pressure Zone Classification

Do both the low and high side pressures fall within Zone C on the classification chart?

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Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone C

Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone D